1. Field of the Invention
This invention relates generally to a television receiver and, more particularly, to apparatus for use with a digital television receiver to assure that it is initially adjusted properly following manufacture or repair.
2. Description of the Background
Presently color television receivers are known in which the majority of signal processing that takes place therein is carried out digitally. That is, the video signal is received in a conventional fashion using a known analog tuning circuit and then, following the tuning operation, the received analog television signal is converted to a digital signal and digitally processed before being subsequently converted back to an analog signal for display on a color cathode ray tube.
Although digital signal processing has many advantages over conventional analog signal processing, one problem that is presented by digital signal processing relates to the state of the circuitry at the time immediately following the manufacture of the set or following servicing of the set by a repair technician. Although conventional analog components and signal processing elements can be easily set to an appropriate value, such as a midpoint of a range, at the time of manufacture and such values will be held until later adjusted, digital circuits employing memory units, registers, and so forth do not have any initial settings and, indeed, cannot be initially set absent some sort of digital, pre-programming source. Examples of some of the various parameters that may be preset in the digital circuitry of a color television receiver are contrast, brightness, hue, color saturation degree, white balance, and perhaps most importantly, horizontal and vertical deflections. The problem being that if the television receiver is turned ON before appropriate initial values are set for the above-identified parameters, it is quite possible that the random or zero values present in the digital memories may be abnormal and outside of tolerated limits. Such abnormal values then would cause adverse influence on the appropriate circuit portions, for example, were the horizontal and vertical amplitudes increased or horizontal and vertical oscillation frequencies decreased drastically, there is a good likelihood that the horizontal or vertical output circuits will be destroyed.